A computer numerical control (CNC) milling machine uses a cutting tool rotated by a spindle to remove material from the surface of a work piece as the work piece is moved with respect to the cutting tool. The work piece is placed on a support surface of the milling machine, and the milling machine needs to know the position of the work piece on the support surface (the X and Y origins), as well as the position of the top of the work piece (the Z origin), in order to calibrate the machine with the “zero” of the work piece. This calibration is done because the milling machine is typically programmed with instructions to move the cutting tool and/or work piece with respect to the X, Y, and Z zero coordinates of the work piece, and determining the X, Y, and Z origins are important to make sure a design is cut into the work piece at the proper location. In some milling machines, a user manually enters the X, Y, and Z origins into a computer connected to the milling machine. The X and Y origins can be determined by the user measuring the distance between the edges of the support surface and the location of a corner of the work piece. The Z origin can be determined by the user measuring the thickness of the work piece. After the calibration is complete, the milling machine carves a design into the work piece.